A method of producing cumene by reacting benzene with propylene, a method of producing cumene hydroperoxide by oxidizing cumene, and a method of producing phenol and acetone by subjecting cumene hydroperoxide to acid cleavage are each already known. A method of a combination of these reactions is a method for producing phenol generally called the cumene process and is currently a mainstream method for the production of phenol.
The cumene process has a characteristic of producing acetone simultaneously. This simultaneous production is advantageous when both phenol and acetone are demanded. However, if the amount of the acetone simultaneously produced is in excess of demand, the economic efficiency can be deteriorated due to the price difference between acetone and propylene which is a raw material. In view of this, methods have been then proposed in which the acetone simultaneously produced is converted into propylene through various approaches and is reused as a raw material in the cumene process.
Acetone is readily hydrogenated to be converted into isopropyl alcohol. A process has been proposed in which the thus obtained isopropyl alcohol is dehydrated into propylene and the propylene is reacted with benzene to give cumene. That is, acetone is reused as a material in the cumene process by being converted into propylene through reactions in two stages (Patent Documents 1 and 2). However, such a process may in some cases cause a phenomenon where the reaction activity and the propylene selectivity deteriorate sharply when LHSV (liquid hourly space velocity) is increased at the time of the dehydration reaction of isopropyl alcohol. Developments of techniques for the dehydration reaction from isopropyl alcohol to propylene with a higher productivity have been demanded from industry. Further, the use of a general dehydration catalyst may concurrently induce other reactions such as the oligomerization reaction of formed propylene to thereby produce impurities as by-products; and the selectivity decreases, which is problematic.